Length-Dependent Prolongation of Force Relaxation Is Unaltered by Delay of Intracellular Calcium Decline in Early-Stage Rabbit Right Ventricular Hypertrophy
Michelle M. Monasky, Carlos A. A. Torres, Paul M. L. Janssen
Abstract
Chronic pressure overload can result in ventricular hypertrophy and eventually diastolic dysfunction. In normal myocardium, the time from peak tension to 50% relaxation of isolated cardiac myocardium is not directly determined by the time for calcium decline. This study aims to determine whether the time for calcium decline is altered with a change in preload in early-stage hypertrophied myocardium, and whether this change in time for calcium decline alters the rate of relaxation of the myocardium. Young New Zealand white rabbits underwent a pulmonary artery banding procedure and were euthanized 10 weeks later. Twitch contractions and calibrated bis-fura-2 calcium transients were measured in isolated thin right ventricular trabeculae at optimal length and with the muscle taut. Systolic calcium, calcium transient amplitude, and time from peak tension to 50% relaxation all increased with an increase in preload for both hypertrophied and sham groups. Time for intracellular calcium decline increased both with an increase in preload and an increase in extracellular calcium concentration in hypertrophied myocardium but not in sham, while time from peak tension to 50% relaxation did not significantly change between groups under either condition. Also, time for intracellular calcium decline generally decreased with an increase in extracellular calcium for both hypertrophied and sham groups, while time from peak tension to 50% relaxation generally did not significantly change in either group. Combined, these results indicate that the mild hypertrophy significantly changes calcium handling, but does not impact on the rate of force relaxation. This implies that the rate-limiting step in force relaxation is not directly related to calcium transient decline.
This research output has an Altmetric Attention Score of 1. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 07 December 2017.
All research outputs
#20,453,782
of 23,009,818 outputs
Outputs from Frontiers in Physiology
#9,478
of 13,760 outputs
Outputs of similar age
#374,467
of 439,388 outputs
Outputs of similar age from Frontiers in Physiology
#219
of 324 outputs
Altmetric has tracked 23,009,818 research outputs across all sources so far. This one is in the 1st percentile – i.e., 1% of other outputs scored the same or lower than it.
So far Altmetric has tracked 13,760 research outputs from this source. They typically receive more attention than average, with a mean Attention Score of 7.6. This one is in the 1st percentile – i.e., 1% of its peers scored the same or lower than it.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 439,388 tracked outputs that were published within six weeks on either side of this one in any source. This one is in the 1st percentile – i.e., 1% of its contemporaries scored the same or lower than it.
We're also able to compare this research output to 324 others from the same source and published within six weeks on either side of this one. This one is in the 1st percentile – i.e., 1% of its contemporaries scored the same or lower than it.
